This page contains comprehensive information for administrators on how to configure skins on a wiki. Please refer to Help:Skins for general skin information and Manual:Skinning for developer information on creating new skins.

For any skin in your /skins directory that you wish to use, you must enable it in your LocalSettings.phpManual:LocalSettings.php file.
For example, to enable Vector, add the following.
If you have multiple skins, each must be enabled with a separate statement:

Additional steps may be required depending on the choice of skin.
Detailed installation instructions are available on each skin's page on mediawiki.org; for example, for Vector see Skin:Vector#Installation. Instructions for all other skins are analogous.

Changing these value on an existing wiki will automatically change the setting of all users who have been using the previous default skin. There is a maintenance script to change users' preferences (userOptions.php), but you will most likely not need to use it.

Users can also specify their own CSS rules by creating the page "User:Username/common.css".
The CSS on this page is then applied to whatever skin the user is using.
If the website is changed to a different default skin, the user's custom CSS will continue to work just as before.
This feature can be enabled by setting $wgAllowUserCssManual:$wgAllowUserCss to true in LocalSettings.php.
A user can also apply CSS to a specific skin by creating the page "User:Username/skinname.css".
If a user uses the MonoBook skin for example, they would edit the page Special:MyPage/monobook.css.

The system administrator can completely remove the "Skin" option so that it does not show up at all in User Preferences. This makes sense if your site will use a customized skin and would not look right in any other skin.

To do it, add a new line containing the following code to LocalSettings.php. It will remove the "Skin" option from preferences and the possibility to use the useskin parameter in the URL.